That's part of it. But writers have stylistically improved over the past 200 years or so since Defoe was writing. Most 19th century writers lack refinement and have an inability to even make images (i.e. scraps of prescient detail that actually mean). The notion of the 'real' of course, changed drastically at the end of the 19th century. The details that mattered weren't one of setting, but one of psychology and emotion. It makes sense that reading a style that devalues meaningful detail replacing it with willy-nilly detail would be frustrating to read.

I absolutely agree, but Robinson Crusoe was not one of them.

There was a lot of drivel printed as you point out, just plain drivel. Charles Dickens was one of the only English novelists that wasn't drivel, he wrote in the vernacular, and he was printed early 19th-century. Don't get too carried away condemning anything printed before the late 19th-century.

Voltaire was printed in the 18th century. Probably there was more lost to us printed in the 18th century but burned.

The political tracts are what tends to survive from England from the late-18th to the late-19th centuries. Works from Ireland? No. Works from Scotland? No. Why? Because they were burnt.